Thermal-Load Analysis of Semi-Basement-Type Single-Span Greenhouse

Purpose The proposed study was performed to investigate thermal-load characteristics required for heating of a semi-basement-type greenhouse, which is different from conventional greenhouses. Methods To determine whether the thermal load of a semi-basement-type greenhouse is different from that of conventional greenhouses, values of the heat-transfer coefficient, heat-transmission coefficient of greenhouse cover, soil heat flux, and infiltration heat-transfer coefficient that were calculated and compared against data obtained from extant studies. Results The heat-transfer coefficient was estimated to be 2.6 W/m 2 °C, whereas values of the heat-transmission coefficient for greenhouse cover, soil heat flux, and infiltration heat-transfer coefficient (obtained using the heat-balance relation) equaled 2.1 W/m 2 °C, − 10.3 W/m 2 , and 0.1 W/m 2 °C, respectively. Values of the greenhouse cover and infiltration heat-transfer coefficients were observed to lie within the feasible range of data reported in extant studies. That said, values of the greenhouse heat-transfer coefficient and soil heat flux, respectively, measured slightly higher and lower compared to corresponding values observed in extant studies. Conclusions Although semi-basement-type greenhouses occupy an underground space, their observed thermal performance is not much different from that of greenhouses installed level with the earth’s surface.